protected override void OnSizeAllocated(Gdk.Rectangle allocation)
{
int lw, lh;
layout.Width = (int)(allocation.Width * Pango.Scale.PangoScale);
layout.GetPixelSize (out lw, out lh);
TooltipText = layout.IsEllipsized ? text : null;
HeightRequest = lh;
base.OnSizeAllocated (allocation);
}